


Demon on My Shoulder

by Joel7th



Category: X-Men (Movieverse), X-Men - All Media Types, X-Men: First Class - Fandom
Genre: Additional tags will be added, Alternate Universe, Demon!Charles, Fantasy, M/M, Rating May Change, Some violence and strong language, magus!Erik
Language: English
Status: In-Progress
Published: 2019-12-21
Updated: 2019-12-21
Packaged: 2021-02-26 02:02:57
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 3,883
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/21885655
Author URL: https://archiveofourown.org/users/Joel7th/pseuds/Joel7th
Summary: Magus Erik Lehnsherr screwed up an exorcism. Now he had a demon on his shoulder.
Relationships: Erik Lehnsherr/Charles Xavier
Comments: 2
Kudos: 10





	Demon on My Shoulder

Erik had screwed up.

Erik did not normally screw up; in fact, his track record so far had been flawless. He was no green novice, damn it; got the experience — half a decade’s worth; the skills constantly honed by the years; the elemental powers — metal, a rare and sought-after element — to back up his skills; a reservoir of spells — white and black both; and even the _sechster Sinn_ that proved to be invaluable in this field — had saved his life a couple times throughout his perilous career.

All in all, he should not screw up.

Yet he had. Spectacularly.

It did not occur to him that something had gone awry during his last exorcism until Erik was jolted awake like someone had dumped a bucket of ice over his naked body. He was lying on his side atop his crumpled, unwashed sheets, the cover pulled up to his waist when he vaguely felt a pricking sensation in his left shoulder. His sleep-addled brain had attributed it to a bug of some sort — there was no shortage of creepy-crawlies in this rundown apartment, given its squalid state and his own negligence. His eyes squeezed shut, chasing after his sleep that was starting to scram, he mumbled a curse and blindly squashed the spot. A high-pitched yelp entered his ears, sending an electric current along his spine down to his toes and making his hair stand on end. His sleepiness fled him like a horde of hell hounds were chasing after its tail, leaving Erik fully awake and very much aware that there was someone else beside him in his apartment, because that yelp sure as hell couldn’t come from a mosquito or a roach. That was where horror began filling his brain with the speed of a running tap: he was one-hundred percent sure he had gone to bed alone last night — had crawled back home past the witching hour and passed out the moment his body collapsed into the mattress. There should never be an extra body in his bed, especially one whose presence or warmth or any living signs he could. not. felt. At all.

_Scheiße!_

“I’m sorry I accidentally pricked you with my claw but did you really have to squash me like that? It hurts!”

Masculine, young and unmalicious and properly right beside him; those were what Erik could deduce from the complaining voice. Also, it had a British accent, which was beside the point; a number of demons he’d encountered favored a British accent, odd yet insignificant. If anything, it eased his anxiety a little to know for now, the speaker bore no killing intent towards him because what kind of murderous demons would apologize? If he had wanted to take Erik’s life, he would be a corpse well into rigor mortis.

What did he want? Erik needed to find out.

As calm as he could maintain with an uninvited stranger invading his personal space — he praised himself for doing an excellent job here, Erik kept his movement minimum save for a tilt of his head to glance sideway at the ceiling, where a full-body mirror was nailed to the ceiling. A silver mirror was an essential item in every magus’s household so that they could check for any supernatural presence that might be invisible to the naked eye, because its enchanted surface, even dulled by a layer of fine dust like the one in Erik’s possession, dispelled the craftiest glamor to bare the object’s true form. This was exactly the situation which called for its use.

Okay, so Erik did not let out an undignified yelp, maybe just a soundless gasp, when the mirror showed him the source of the voice: a humanoid blotch of the darkest ink pressing against his body in a caricature of an affectionate spooning. His chin rested atop Erik’s head. His huge chiropteran wings spread wide, covering most of the cream-colored mattress and his tail with an arrowhead for the tip relaxed and lolled over the edge of the bed. And sure enough, the black smear that qualified for his hand was splaying on his shoulder, the long tendrils Erik supposed were his claws dangerously close to grazing his skin. At least that explained the prick. He got to examine the wound later, when all of this was over, somehow. Wounds caused by a demon’s claws were no joke and he might need to pay Logan’s clinic for a shot, just to be on the safe side; who knew what sorts of infernal pathogens those claws were carrying?

Well, if having a demon in his bed and thinking about vaccination didn’t top his list of weirdness this year — and he had encountered some really weird shits in his line of work, Erik had no idea what could.

What now? He didn’t know what type of hellspawn this was, nor could he gauge his powers or make a guess of what tricks he had up his figurative sleeves. That put Erik at a severe disadvantage and he hated being disadvantaged. He flicked his gaze over the clock on the nightstand and knew it was only six in the morning. The sun was already up but his full magical power was not: it needed another two hours for Erik to be at his peak, which was prerequisite requirement for some of his most effective battling spells. He couldn’t wait that long. His mind was racing at the speed he normally forced his old car on highways, always pushing the speed limit. He could bark a monosyllabic spell, one of his proud, unique inventions for emergencies. It wasn’t too strong and Erik doubted it could do any actual harm to the creature of hell, but he could count on it to startle the demon, buying him a few precious seconds to untangle himself from him and summon the blade hidden under the mattress. Even a mediocre magus should know to always arm himself for ambushes, and Erik was no mediocre magus. His apartment was practically a well-stocked arsenal of magical weapons. Once he had his hand on his blade, forged of pure iron and engraved with runes, he got one chance for a strike. Would a jab to the heart be enough to incapacitate him?

“The answer is no,” the young man’s voice rang in Erik’s head, sounding very posh and slightly amused. “And that relies heavily on the premise that you could find my heart. Hint: it’s not in my chest and nowhere near my body.”

Erik’s muscles tensed like he just witnessed Cerberus catching a Frisbee in his backyard (he didn’t even have a backyard!). Hold the fuck up! If he heard the voice in his head then this demon was...

“The telepathic type,” the demon filled in for him. “Thank you for noticing.”

The highest-ranking type in the seven rings of hell, telepathic demons were the nobles in Satan’s court. Also, a colossal pain in the ass to deal with, a ubiquitously acknowledged fact in every magic scroll his bastard of a mentor had made Erik cram during his teenage years. Erik himself had never met one, so his inexperience added more to his snags.

“I’m flattered,” the damned thing chuckled, fucking chuckled. Erik felt a light tremor along his back. “By the way, you were thinking quite loudly about zapping me with a spell. I strongly advise not to do it.”

“Give me one good reason why,” Erik said.

“Because—”

There, a window of opportunity where the demon was distracted and Erik would be a fool to let it slip. Keeping his thoughts directed to their reflection in the mirror, he acted in milliseconds.

A spark and Erik got his intended effect: the demon shrieked and recoiled from his body. However, almost instantly he got an unintended effect of pain searing through his entire right arm. He hissed and rolled away from the demon, only to roll of the bed and landed on the cement floor with a thud.

Erik swore colorfully, clutching his arm. Even so, he didn’t forget the blade and called for it with a fraction of his power. The solid weight and metallic coolness in his hand were very reassuring.

“I told you, didn’t I?” The demon’s voice was strained. A brief look into the mirror showed that he was also clutching his right arm.

“The hell was that?” Erik snarled. “What did you do to me?”

“I didn’t do a thing. You did it all to yourself.”

Were his ears deceiving him or the demon actually sounded... hurt?

“Explain!”

There was a tiny sigh before the demon in the mirror shook his head as if he were an adult trying to reason with a petulant brat and failing. Erik found it incredibly vexing. He was tempted to cast another spell; the only thing that stopped him was the throbbing pain in his limb.

“As you’ve experienced it firsthand, you and I are connected, meaning if I got hurt, you would also get hurt, so please don’t shoot another ball of energy at me or stab me even if you’re tempted to do so.”

Did the demon’s words loosen his grip on the blade’s handle? Surely not.

“You may not believe it yet, but I mean you no harm.” The demon sounded sincere, obviously trying to placate him. “As a matter of fact, I don’t want you to get hurt of anything, because if somehow you got killed—”

“You would die with me?” Erik snorted. _Cliché._

The demon huffed. “No, but I would be sent back to Hell, and I don’t want to be back when my business here isn’t done. Satan knows how many miles I have climbed to get out of Hell.”

“How can I tell if you aren’t sent to ensnare me?”

Erik knew he had made tons of enemies in his line of work. He really wasn’t surprised to learn one of them had resorted to demonic summons; in fact, it was one of the oldest tricks in the book, one that proven to be quite effective, much to his irritation.

The demon’s laughter rang in his head, grating his frayed nerves. The sound he made wasn’t awful per se, but it was grating simply because it reminded Erik that his telepathic powers were not to be underestimated and that the magus was under his influence. Erik had no training in shielding himself from telepathy (his mentor must have deliberately withdrawn this crucial lesson, the bastard) and thus was right under his mercy: if he wanted, he could make Erik do the chicken dance or do himself in, and either thought was unnerving enough to make his stomach churn. He fought back a nauseous feeling.

“Sweet Satan, no!” the demon exclaimed, voice still bubbling with laughter. “We telepathic type made a pact to dump any summoning requests of that sort. We have standards, you see. As for the latter, I’m afraid I found myself hopelessly ensnared by you, my friend.”

The demon drawled the last two words, making Erik’s skin crawl. Although he could not make out his face in that inky blotch, he had an impression that the demon was looking quite smug with his effect on him. While his face paled with anger — at himself mostly, the tips of his ears went red and were burning.

Erik glared at his empty mattress, where not even a dimple was visible. “Show yourself,” he demanded. Turning his head every two seconds to look at the ceiling mirror was starting to give his neck a crick. Besides, without the invisible cloaking, Erik could study his form for any weaknesses he could utilize.

“My my, what terrible manners I have,” the demon said, sounding oddly contrite. “This is my first time being in the human world, so I beg your forgiveness for any faux pas I’ve made.”

This is also my first time seeing such a garrulous demon, Erik thought and hoped the demon caught it. If this unconventional loquacity had one redeeming quality, it was the demon’s pleasant voice. The accent kind of helped, too, although Erik wasn’t big on posh British accent — too pretentious for his taste. If he vomited words like a thug, Erik believed he should start researching for a gagging spell.

“I’ve been told that I have a good voice, but thank you.”

Erik took one look at the demon’s corporeal form and dropped his jaw.

Forget everything about finding a demon in bed topping his list of weirdness this year; he had a brand-new champion now.

Because on his bed where a few seconds ago there had been nothing but air (the silver mirror had told him otherwise, though) was a young man sitting with his legs crossed at the knees. With his head propped on one elbow, he nailed his gaze on Erik as his lips curved into a kind half-smile that leaned heavily into the bedroom territory (granted, they were in an actual bedroom). When his tongue peaked out from his mouth to drag along his lips, Erik fought his subconscious urge to mirror him. He considered stabbing himself with the blade still in his hand.

There was nothing strange about the young man appearance-wise, certainly nothing to invoke such reaction from Erik. Nothing except that Erik could count the number of freckles scattered on the side of his thigh, which was due to the fact that he was wearing no pants. Or shirt. Or anything to cover himself for that matter.

A young, attractive man in all his birthday suit’s glory should have been an arousing sight, if you were somehow blind to the pair of bat wings that had just sprouted from his back with a ‘whoosh’, which was impossible because those things were fucking huge, and then the truth about his unholy nature descended upon you like Thor’s hammer, mercilessly pulling you back to reality.

Can’t bear to look too human, huh?

“Put some clothes on,” Erik hissed, tearing his eyes from the magnetizing naked skin.

“Why?” asked the demon in his physical voice, which was the same as his telepathic voice. The confusion was almost genuine.

Could he stab some _human_ common sense into this demon? Probably not, but the temptation was strong.

“Do demons in hell not wear any clothing?”

“Clothing is optional, and I’m comfortable enough in my own skin,” the demon replied, gesturing vaguely at his body. “Besides, I’ve learnt in the short time here that humans are very fond of gawking at uncovered human anatomy.”

“Not me!”

“Liar,” the demon accused, though there was no harshness in his tone, and tapped his temple. “We both know you appreciate a well-proportioned body as much as the next man, and I believe this flesh-bag of mine doesn’t look half-bad. There’s nothing to be embarrassed about it.”

“Until I find a way to get rid of you for good—”

“But you can’t get rid of me. At least not in the near future.”

“I’m very motivated! Now we need to establish some rules if this mess isn’t going anywhere soon.”

Until he found a way to get rid of this demon without offing himself, Erik thought, he guessed he would have to endure.

The demon arched an eyebrow but kept his mouth shut for once. His smile deepened and he leaned a tad forward.

“Number one: clothes on at all times.”

The demon pouted but didn’t retort. In the time it took Erik to blink, clothes had manifested on his body. Nothing too fancy like a tux or a flowing cape, just a plain white button-down and fitting black slacks with suspenders, which Erik appreciated. He even had a pair of shiny black oxfords, which Erik didn’t appreciate because said pair was stepping on his mattress.

He told himself that was the reason for his heated face, and not the delicate-looking collarbone on display due to the top buttons left undone.

The demon smoothed back a few strands of hair that had fallen over his eyes and gave Erik and inquisitive look. “How do I look?”

“If you’re fishing for compliments then you’ll find none.”

The demon shrugged, smiling. “That to me is enough a compliment.”

“Number two: don’t go snooping around in my head like you’ve done unless I give you explicit permission. Got it?”

Disappointment was visible in his downturn lips. He crossed his arms on his chest and pouted. “I promise I won’t do it unless you allow me to,” he said, fanning his wings, “which is torture for me because just so you know, my friend, your mind is rich and absolutely gorgeous and I love to dive into it. I could spend days exploring it and never get bored.”

Erik’d had quite a few people tell him he was good-looking (to flirt with him, mostly), but never had he had someone compliment on his mind. If anything, he believed his mind was a minefield even Erik himself was afraid to tread, courtesy of his mentor.

“Number three: don’t control my mind. _Ever._ The moment you start dipping your fingers into my thoughts and actions, I will end you even if it costs my life.”

The demon held up his palms. “I have no intention to do that, rest assured, my friend.”

“Why don’t you?”

It seemed like a natural thing for a telepathic demon, didn’t it?

A hard frown manifested on his handsome face and Erik could see all the glee and flirtations up until this moment had been flushed away from his being. His wings were still, pressed closed to his body and he straightened his posture. His lips became a thin line. “It’s terribly prejudiced to assume a telepathic demon would go around manipulating people. Yes, there are demons who have no qualms doing that and they give our kind a bad rap. But I’m not one of those. You have my word.”

Erik scoffed. Right, a demon’s word. Totally trustworthy because there had never been a case where a foolish human was duped by a demon and lost everything, including his life. “We’ll see about that,” he said.

“I can see your doubt and suspicion, which is understandable. Will it put you at ease if I do this?”

“Do what?”

The demon opened his right palm and carved an ‘X’ into the flesh with a clawed finger. He closed his injured hand into a fist and squeezed. A couple drops of viscous ink hit the floor and sizzled like boiling oil. When he held up his palm for Erik to see, the blood was gone but the ‘X’ remained in the form of a tattoo. Throughout the process, not for a millisecond had his eyes left Erik’s.

“My word may not have much weight to you, but a blood oath does, doesn’t it?”

That, Erik knew was true. The repercussions for breaking a blood oath was no joke and often quite ugly. Erik was unfortunate enough to have witnessed a few incidents, which had always involved varying degrees of body horror.

“Why did you go so far to earn my trust, which you haven’t, by the way?”

“Like I said,” the demon stressed, as if to show Erik his patience, “we are going to stick together for a while, my friend, and it’d be better if you weren’t boiling with suspicion for me every waking minute.”

“How about telling me your name for a start?”

The demon’s jaws hung open for a solid five seconds because he smiled sheepishly. “It seems I must’ve forgotten my manners. Again. My apologies. My name is Charles Xavier. Nice to meet you.”

He held out his hand, which Erik didn’t shake. Gingerly he retreated it.

“It’s not your true name, isn’t it?”

“My true name only the Dark Prince can pronounce,” Charles said, shrugging, “quite literally. Charles Xavier is my chosen name, and it works just fine whether you want to summon me, bind me or banish me. Go on. Try summoning me. All you have to do is say my name.”

Erik’s mouth opened, refusal ready on his lips, but before the words came out, his curiosity won over. “Charles,” he said, a note of hesitation. “Charles Xavier.”

He felt the effect instantly, a warm presence pressed against his back, making him shiver, while Charles’s spot was empty. Hot breath ghosted over his cheek. When he looked down, he saw semi-transparent fingers intertwined in front of his chest. He blinked, and the ghostly fingers vaporized like dew in sun rays. Charles was sitting cross-legged on the mattress, his eyes fixed on Erik like he was the sole object in the world worth seeing. If anything, he managed to look even smugger. Pleased with his little trick, likely, and the look it painted on Erik’s face.

He had heard countless tales of demons deceiving humans for their gains, but one that teased without malicious intents? Charles was definitely an enigma, and before Erik could figure him out, he had to be on guard, which could be a lot more difficult said than done.

“Are we going to be joined at the hips from now on?” Erik asked.

“No, I can get some distance from you, and vice versa, though I would love for us to be joined at the hips. Besides your gorgeous mind, you also have gorgeous body from what I can tell, and bath time is going to be so much fun.”

His eyes raked slowly over Erik’s lean form as if to prove his point. He wasn’t conscious of his underdressed state until being put under Charles’s thorough scrutiny, which made him ache to grab a shirt. What the heck? Being half-naked around another male was nothing to squirm about; if anything, he had even joined Logan in one of those hot springs the Japanese sure loved. He breathed out of his nose, thinking of something to distract himself from Charles’s eyes.

Charles’s eyes. Yes. Unearthly blue and shimmering in Erik’s dimly lit bedroom and raising an alarming sense of déja vu.

He had seen those eyes before! And the memory was fresh enough that the more he looked into Charles’s eyes, the more he was convinced he’d definitely seen them.

“Why are you stuck with me?” Erik asked, gesturing between themselves. “This... this haunting?”

The smile froze and his eyebrows knitted. He pursed his lips. “I’m hurt, my friend,” he groaned theatrically, causing Erik’s face to crumple up. “No, I’m dying from a shattered heart due to your frost words. How could you forget me already when we just met yesterday?”

Something clicked in Erik’s brain, and like a cog which had been previously jammed was only now cleared, everything fell into place, making sense of all the nonsense which had begun since he found a demon spooning him as if they were goddamn lovers.

They were closer than lovers, in a sense.

“You-you...” Erik sputtered. He rarely sputtered, taking pride in his strength of speech. He only ever did so when he knew he had screwed up.

This was one such cases.

Charles’s eyes lit up like two headlights in a misty night. His tongue darted out and caressed his bottom lip. “We’ll meet again, Erik. I did say that when we parted, didn’t I? And I always make good on my words.”

_TBC_


End file.
